The invention relates to a planetary transmission for automotive vehicles. The transmission has compound gear elements of the well known Simpson type.
A multiple speed torque converter transmission for rear wheel drive vehicles is shown in German Offenlegungsschrift Published Specification 34 17 703. That transmission has a Simpson-type planet gear system. The input member of the Simpson-type planet gear system comprises two clutches CL.sub.2 and CL.sub.3, by which driving torque is selectively connected to the common sun gear of the planet gear system or to the annulus of the front set during operation in the forward gear speeds. In addition, the Simpson-type planet gear system of the prior art publication comprises two brakes B.sub.2 and B.sub.3 for locking the common sun gear during operation in the second gear speed and for locking the planet gear carrier of the rear set during operation in the first gear speed and the reverse gear speed, respectively. It further comprises an overrunning clutch OWC.sub.2 arranged parallel to the friction brake B.sub.3 so as to produce a driving torque flow path in the first gear speed only in one direction. In this case the planet gear carrier of the forward set and the annulus of the rear set of the Simpson-type planet gear system are connected drivably to the driving shaft.
The front portion of the driven shaft adjacent the common gun gear of the prior art design is provided with a center bore and with radial ports for supplying lubricating oil to the common sun gear mounted on the driven shaft by means of bearing bushings and to the planet gears that engage the sun gear.
The center bore of the driven shaft of the prior art design connected to the radial ports causes a noticeable weakening of the driven shaft, so that it can transmit torque only in a restricted torque range. On the other hand, the loads arising in the other elements of the planet-gear system are not so high. In a specific design these other elements would be capable of transmitting torque in a higher torque range.
It is an object of the invention to use the torque transmitting elements of a known design, as disclosed in the reference publication, which was designed for a torque range not exceeding 450 Newton-meters, and to adapt it for transmitting torque in a higher range of up to 750 Newton-meters while retaining as many as possible of the components of the known planet gear system.